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  Image forming apparatusUSPTO Application #: 20060209151Title: Image forming apparatus Abstract: A transfer member and a downstream-side neutralizing electrode make a contact with a rear portion of an intermediate transfer belt within a contact region. A transfer voltage with an opposite polarity to a regularly charged polarity of a toner is applied to the transfer member. A voltage with a same polarity as the regularly charged polarity of the toner is applied to the downstream-side neutralizing electrode. (end of abstract) Agent: C. Irvin Mcclelland Oblon, Spivak, Mcclelland, Maier & Neustadt, P.C. - Alexandria, VA, US Inventors: Takahiro Tamiya, Katsuhiro Echigo, Hajime Oyama, Hisashi Kikuchi USPTO Applicaton #: 20060209151 - Class: 347103000 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20060209151. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present document incorporates by reference the entire contents of Japanese priority document, 2005-078985 filed in Japan on Mar. 18, 2005, 2005-080813 filed in Japan on Mar. 22, 2005 and 2005-361965 filed in Japan on Dec. 15, 2005. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to an image forming apparatus that performs a primary transfer of a toner image formed on an image carrier to an intermediate transfer belt that is driven while contacting with the image carrier, and a secondary transfer of a toner image formed on the intermediate transfer belt to a recording medium. [0004] 2. Description of the Related Art [0005] An image forming apparatus that primarily transfers a toner image formed on an image carrier to an intermediate transfer belt that is driven while contacting with the image carrier, and secondarily transfers a toner image formed on the intermediate transfer belt to a recording medium is well known, such as a copying machine, a printer, a facsimile machine, and a multifunction product (see, for example, Japanese Patent No. 3346063). In such an image forming apparatus, a small amount of toner adheres around the toner image transferred on the intermediate transfer belt in a scattered manner, which is called a transfer dust. FIG. 15 is a schematic diagram for illustrating a source of the transfer dust and conventional measures against the transfer dust. [0006] In FIG. 15, an image carrier 3A configured by a drum-like photoconductor is rotationally driven in a direction of arrow, and a toner image including toner particles T is formed on the image carrier 3A during the rotational driving. Toner particles T are charged to a regular polarity, namely, a minus polarity in FIG. 15. An intermediate transfer belt 4A, which is driven in a direction of arrow A, is disposed to face the image carrier 3A. A pair of guide rollers 21A, 22A is pressed on a surface of the image carrier 3A via the intermediate transfer belt 4A, so that the intermediate transfer belt 4A contacts with the surface of the image carrier 3A. [0007] When a range between the most upstream-side position XA of a portion of the intermediate transfer belt contacting with the image carrier 3A and the most downstream-side position YA thereof is called "contact region NA", a transfer member 13A abuts on a rear portion of the intermediate transfer belt 4A positioned within the contact region NA. The transfer member 13A is formed of a blade. A transfer voltage with an opposite polarity to a regularly charged polarity (a plus polarity in this example) of toner particles T is applied to the transfer member 13A by a power source 23A. Thereby, an electric field is formed between the image carrier 3A and the intermediate transfer belt 4A so that a toner image on the image carrier 3A electrostatically moves to a surface of the intermediate transfer belt 4A and the toner image is primarily transferred to the intermediate transfer belt 4A. Reference letter T1 is attached to toner particles constituting a toner image transferred on the intermediate transfer belt 4A. The toner image primarily transferred on the intermediate transfer belt 4A in this manner is secondarily transferred on a recording medium that is not shown in FIG. 15 and the toner image is fixed, so that a final image can be obtained. [0008] A wedge-shaped inlet side space SIA is defined between a portion of the intermediate transfer belt positioned on an upstream-side from the contact region NA where the intermediate transfer belt 4A contacts with a surface of the image carrier 3A and the image carrier 3A, and a wedge-shaped outlet side space SOA is similarly formed between a portion of the intermediate transfer belt positioned on a downstream-side from the contact region NA and the image carrier 3A. [0009] As described above, since the transfer member 13A applied with the transfer voltage with a plus polarity contacts with a rear surface of the intermediate transfer belt 4A, charges with the plus polarity are given to the rear surface of the intermediate transfer belt 4A, and the charges move to regions of the inlet side space SIA and the outlet side space SOA along the rear surface of the intermediate transfer belt 4A. Furthermore, charges are retained within the intermediate transfer belt 4A and the charges retained reach the region of the outlet side space SOA according to movement of the intermediate transfer belt 4A. In the inlet side space SIA and the outlet side space SOA, therefore, discharge occurs between the intermediate transfer belt 4A and the image carrier 3A, so that the polarity of toner particles T of a portion of the toner image on the image carrier 3A and the polarity of toner particles T1 of a portion of the toner image transferred on the intermediate transfer belt 4A are reversed to a plus polarity due to the discharge. Toner particles whose polarity is reversed in this manner are electrostatically scattered on a surface near the toner image to cause transfer dust to be generated. [0010] To prevent the generation of transfer dust, a constitution that the intermediate transfer belt 4A is neutralized by applying voltage having the same polarity (the minus polarity in FIG. 15) as the regularly charged polarity of toner particles to the respective rollers 21A, 22A shown in FIG. 15 has been proposed. The constitution prevents discharge from occurring in the inlet side space SIA and the outlet side space SOA by neutralizing the intermediate transfer belt 4A, thereby preventing reverse of the toner particle polarity. However, there is a possibility that the intermediate transfer belt 4A cannot be neutralized sufficiently utilizing only this constitution, especially, charges remain on the intermediate transfer belt 4A that has reached the outlet side space SOA, so that the remaining charges keep discharging in the outlet side space SOA, which can cause transfer dust on the intermediate transfer belt. SUMMARY OF THE INVENTION [0011] It is an object of the present invention to at least solve the problems in the conventional technology. [0012] An image forming apparatus according to one aspect of the present invention performs a primary transfer of a toner image formed on an image carrier to an intermediate transfer belt that is driven while contacting with the image carrier, and a secondary transfer of the toner image on the intermediate transfer belt to a recording medium to obtain a recorded image. The image forming apparatus includes a transfer member that makes, when a range of a portion of the intermediate transfer belt contacting with the image carrier, which is positioned between the most upstream-side position and the most downstream-side position in a moving direction of the intermediate transfer belt, is defined as a contact region, a contact with a rear portion of the intermediate transfer belt within the contact region, as a primary transfer device that performs the primary transfer of the toner image on the image carrier to the intermediate transfer belt; and a downstream-side neutralizing electrode that makes a contact with the rear portion of the intermediate transfer belt, which is positioned at a downstream-side in the moving direction of the intermediate transfer belt from a position where the transfer member makes a contact with the intermediate transfer belt and at an upstream-side in the moving direction of the intermediate transfer belt from the most downstream-side position. A transfer voltage with an opposite polarity to a regularly charged polarity of a toner is applied to the transfer member. A voltage with a same polarity as the regularly charged polarity of the toner is applied to the downstream-side neutralizing electrode. [0013] An image forming apparatus according to another aspect of the present invention performs a primary transfer of a toner image formed on an image carrier to an intermediate transfer belt that is driven while contacting with the image carrier, and a secondary transfer of the toner image on the intermediate transfer belt to a recording medium to obtain a recorded image. The image forming apparatus includes a transfer member that makes, when a range of a portion of the intermediate transfer belt contacting with the image carrier, which is positioned between the most upstream-side position and the most downstream-side position in a moving direction of the intermediate transfer belt, is defined as a contact region, a contact with a rear portion of the intermediate transfer belt within the contact region, as a primary transfer device that performs the primary transfer of the toner image on the image carrier to the intermediate transfer belt; and an upstream-side neutralizing electrode that makes a contact with the rear portion of the intermediate transfer belt, which is positioned at an upstream-side in the moving direction of the intermediate transfer belt from a position where the transfer member makes a contact with the intermediate transfer belt and at a downstream-side in the moving direction of the intermediate transfer belt from the most upstream-side position. A transfer voltage with an opposite polarity to a regularly charged polarity of a toner is applied to the transfer member. A voltage with a same polarity as the regularly charged polarity of the toner is applied to the upstream-side neutralizing electrode. [0014] An image forming apparatus according to still another aspect of the present invention performs a primary transfer of a toner image formed on an image carrier to an intermediate transfer belt that is driven while contacting with the image carrier, and a secondary transfer of the toner image on the intermediate transfer belt to a recording medium to obtain a recorded image. The image forming apparatus includes a transfer member that makes, when a range of a portion of the intermediate transfer belt contacting with the image carrier, which is positioned between the most upstream-side position and the most downstream-side position in a moving direction of the intermediate transfer belt, is defined as a contact region, a contact with a rear portion of the intermediate transfer belt within the contact region, as a primary transfer device that performs the primary transfer of the toner image on the image carrier to the intermediate transfer belt; a downstream-side neutralizing electrode that makes a contact with the rear portion of the intermediate transfer belt, which is positioned at a downstream-side in the moving direction of the intermediate transfer belt from a position where the transfer member makes a contact with the intermediate transfer belt and at an upstream-side in the moving direction of the intermediate transfer belt from the most downstream-side position; and an upstream-side neutralizing electrode that makes a contact with the rear portion of the intermediate transfer belt, which is positioned at an upstream-side in the moving direction of the intermediate transfer belt from a position where the transfer member makes a contact with the intermediate transfer belt and at a downstream-side in the moving direction of the intermediate transfer belt from the most upstream-side position. A transfer voltage with an opposite polarity to a regularly charged polarity of a toner is applied to the transfer member. A voltage with a same polarity as the regularly charged polarity of the toner is applied to the downstream-side neutralizing electrode and the upstream-side neutralizing electrode. [0015] The above and other-objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0016] FIG. 1 is a schematic diagram of an example of an image forming apparatus; [0017] FIG. 2 is a schematic diagram for illustrating a constitution for transferring a toner image formed on an image carrier shown in FIG. 1 to an intermediate transfer belt; [0018] FIG. 3 is a schematic diagram for illustrating a relationship between a transfer blade, a downstream-side neutralizing blade and an upstream-side neutralizing blade, conductive adhesive covering proximal portions of the blades, and a terminal for a power source; [0019] FIGS. 4A to 4D are schematic diagrams for illustrating an example in which the transfer blade, the downstream-side neutralizing blade, and the upstream-side neutralizing blade are directly fitted into grooves formed in a supporting member; [0020] FIGS. 5 and 6 are schematic diagrams for illustrating an example in which the transfer blade, the downstream-side neutralizing blade, and the upstream-side neutralizing blade are made of metal; Continue reading... Full patent description for Image forming apparatus Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Image forming apparatus patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Image forming apparatus or other areas of interest. ### Previous Patent Application: Liquid ejection apparatus Next Patent Application: Driving apparatus Industry Class: Incremental printing of symbolic information ### FreshPatents.com Support Thank you for viewing the Image forming apparatus patent info. IP-related news and info Results in 1.21546 seconds Other interesting Feshpatents.com categories: Medical: Surgery , Surgery(2) , Surgery(3) , Drug , Drug(2) , Prosthesis , Dentistry |
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